1. Technical Field
The present invention relates to a method of inspecting defects in the circuit pattern of a substrate.
2. Description of the Related Art
With the recent development of the electronics industry, the requirement that electronic parts be of high functionality has rapidly increased, and thus methods of inspecting the electrical characteristics of substrates when substrates are manufactured are also required to be of high precision, high speed and low cost. Meanwhile, although the requirements for high-speed measurement ensuring high reliability are strict, there is no efficient measurement method satisfying such requirements, and thus contact probe methods are currently being performed.
FIG. 1 is a sectional view showing a conventional apparatus for inspecting defects in a circuit pattern using contact pin probes. Hereinafter, a conventional apparatus and method for inspecting defects in a circuit pattern will be described with reference to FIG. 1.
The conventional apparatus for inspecting defects in a circuit pattern includes two pin probes 11 and 12, a voltage source 13 and an ammeter 14.
The first pin probe 11 is installed to come into contact with the inspection target circuit pattern 16 of a substrate 15, and inputs a voltage received from the voltage source 13 to the inspection target circuit pattern 16. Therefore, a conical portion of the first pin probe 11 is connected to the inspection target circuit pattern 16, and the portion of the first pin probe 11 which is opposite the conical portion is connected to the voltage source 13 through the lead wire of the first pin probe 11.
The second pin probe 12 is installed to come into contact with a connection circuit pattern 17, of which the electrical connection with the inspection target circuit pattern 16 is desired to be examined. Therefore, a conical portion of the second pin probe 12 is connected to the connection circuit pattern 17, and the portion of the second pin probe 12 which is opposite the conical portion is connected to the lead wire of the first pin probe 11.
The ammeter 14 is a component for measuring current flowing through a closed circuit, and is installed in series with lead wires connected to the first pin probe 11 and the second pin probe 12.
A conventional method of inspecting defects in a circuit pattern is described below.
When the inspection target circuit pattern 16 is normally connected to the connection circuit pattern 17, current flows from the voltage source 13 sequentially through the first pin probe 11, the inspection target circuit pattern 16, the connection circuit pattern 17, and the second pin probe 12. The current is measured by the ammeter 14, and the entire resistance can be measured by applying the current to the formula of Ohm's law, that is, R=V/I. Theoretically, when the inspection target circuit pattern 16 is normally connected to the connection circuit pattern 17, the resistance must be ‘0’. However, since there are resistances of the lead wires and the pin probes 11 and 12 themselves, the entire resistance is not ‘0’ and is derived as a relatively small value.
In contrast, when the inspection target circuit pattern 16 is not normally connected to the connection circuit pattern 17, current does not flow through a closed circuit, and the resistance becomes infinite.
Accordingly, the above resistances are compared with each other, and thus whether defects are present in the circuit pattern can be examined.
However, as described above, in the case where the contact pin probes 11 and 12 are used both in the inspection target circuit pattern 16 and in the connection circuit pattern 17, even if the circuit patterns are not normally connected, the circuit patterns may be measured as if they were normally connected to each other due to the contact pressure of the pin probes 11 and 12. That is, there is a problem in that the occurrence of erroneous measurements may increase.
Further, there is a problem in that the pin probes 11 and 12 come into contact with all unit circuit patterns, thus increasing the time required for measurements.